Chemical ecologist Max Suckling at the Institute for Plant and Food Research Ltd., and summer student Rachael Sagar use Pavlovian conditioning to train bees to stick out their tongues, or proboscises, at the scent of odors produced by tuberculosis-causing bacteria.

A lot changes in a child’s body over the course of development, and not all changes occur linearly: gene expression can fluctuate, and organs can perform different functions on the way to their final purpose in the body. Here are some of the key deve